The present invention concerns a milk-line valve. It comprises a slide, a connector, and a saddle. A port in the saddle opens into the milk line through an annular seal. The slide obstructs the seal. When the connector is inserted, it moves the slide into a position in which it unblocks the port and allows it to communicate with an opening in the connector. The slide and connector can be forced against the seal by connector guides.
A milk-line valve of this type is known from DE 4 003 367 A1 for example. It is used in the dairy industry to connect a milking machine to a milkline. The connector is introduced into the guides, forcing the slide out of its port-blocking position, until the opening in the connector coincides with the port in the saddle. The guides are rigid and specially shaped to force the saddle against the seal.
It is difficult to manufacture the parts precisely enough to attain precisely the prescribed force. Furthermore, the parts tend to eventually deform and the seal to wear out, affecting the level of force. These factors can make the seal too tight or too loose. The slide will no longer be able to move back and forth freely, and the seal can leak. The saddle in the known milk-line valve is screwed to the line. Such connections, however, take time to screw together and can eventually loosen and shift the saddle out of its proper position on the milk line.